refactor(commands): separate commands and its core into two folders (#32)

- I think it would be better if one for commands only, one for the spec
handling core logic so people won't be confused by the core logic inside
the commands folder (cleaner I guess)
- Regen docs

commands/sys/leaf.go

@@ -1,14 +1,14 @@
 package sys
 
 import (
-	"github.com/versenilvis/iris/commands/core"
+	"github.com/versenilvis/iris/spec"
 )
 
 func init() {
-	core.Register(&core.Spec{
+	spec.Register(&spec.Spec{
 		Name:        "leaf",
 		Description: "Create and interact with your leaf projects",
-		Subcommands: []core.Subcommand{
+		Subcommands: []spec.Subcommand{
 			{Name: "completion", Description: "Dump the shell completion script"},
 			{Name: "create", Description: "[init] Create a new Leaf PHP project"},
 			{Name: "project name", Description: "Name of the project"},
@@ -27,7 +27,7 @@ func init() {
 			{Name: "uninstall", Description: "Uninstall a package"},
 			{Name: "update", Description: "Update leaf cli to the latest version"},
 		},
-		Options: []core.Option{
+		Options: []spec.Option{
 			{Name: "-h", Description: "Do not output any message"},
 			{Name: "-V", Description: "Display this application version"},
 			{Name: "--ansi", Description: "Force ANSI output"},